Ok thought I'd add in my 2 cents on this one. First off I have a CCS in my reef tank...and he doesn't bother anything in the tank. Not my corals, not my shrimp, not my feather duster, heck he only goes after the snails to get the algea off of the shells. At times I'm starting to believe that people simply clump the CCS with all other starfish when it comes to what they eat. Second point is that I've had my CCS since the begining...before I even knew what cycling was...heck before I knew the difference between SPS & LPS corals.
All I can do is talk from experience with my CCS and that is that they LOVE red kelp, and that they are great cleaners of red algea. Any time the lovely red color has started to creep up on my tank my littl CCS is working his way to it to eat it ALL up. Now as for his legs being curled up there are one of two options, 1) if just the tips are curled up this is normal, from what I've observed it seems to have "taste buds" at the end of the feet that tell it where food can be found. 2) if the whole foot is curled this normally means that it is having a heard time adjusting and should be put into a place of his own to "calm down".
Just some more info on your CCS is that he is not a "true starfish" but more closely related to a bristlestar. Plus don't force him to feed by placing him on food...there is only a 50/50 chance he will take it, I've found placing the food near my star will get him more active for the food item then planting him on it. Also remember they are SLOW eaters taking time to eat what they have caught. Now I may not be a "expert" on a CCS but these are just a few of the observations I have noted on mine.
Peace,
DHS